说文解字

Compiled by Eastern Han scholar Xu Shen 许慎 (Xǔ Shèn) around 100 CE and presented to Emperor An in 121. It analyzes 9,353 characters under 540 radicals (部首), and was the first work to systematically use the 六书 (liùshū) — the six categories of Chinese character formation (pictograph, ideograph, etc.). Still cited daily by anyone reading classical texts.

Often used colloquially as a verb-like phrase: 给我说文解字一下 'parse the characters for me' / 'break it down for me' — borrowing the title to mean 'explain word-by-word'.